Reaction Wheel Assemblies (RWAs) are routinely deployed onboard satellites and other vehicles for attitude adjustment purposes. By common design, an RWA contains a rotor including a rotor shaft, which is fixedly joined to an inertial element (e.g., an outer rim or ring) by way of a suspension web. The rotor is typically mounted within a housing assembly having upper and lower halves, which are sealingly joined to enclose the rotor. The opposing ends of the rotor shaft are received within cylindrical cavities or bores provided in the RWA housing assembly. Spin bearings, such as duplex pair ball bearings, are positioned around the opposing shaft ends to produce a rotor suspension, which generally limits freedom of rotor motion relative to the housing in all directions except for rotation about a spin axis. During operation of the RWA, a spin motor drives rotation of the rotor about a spin axis at a relatively high rate of speed to create momentum. When it is desired to adjust the attitude of the host vehicle, control circuitry commands the spin motor to alter the rotational speed of the rotor and, therefore, the momentum of the RWA. Due to this change in momentum, a controlled output torque is generated, which is transferred from the RWA to the host vehicle to effectuate the desired attitude adjustment.
As satellites increase in number and decrease in size, a demand has arisen for increasingly compact, lightweight, relatively low cost, and readily manufacturable RWAs adapted for deployment onboard so-called “small satellites” or, more simply, “smallsats.” Although a universal definition is yet to be established, a satellite weighing less than 400 kilograms is often considered a “small satellite.” Small satellites include, for example, miniaturized cube-shaped research and communication satellites commonly referred to as “cubesats.” The torque output requirements of a particular RWA may be eased when deployed onboard a small satellite; however, most, if not all of the remaining design requirements of the RWA become increasingly stringent in the small satellite environment. Part count, weight, size, power requirements, complexity, and the like are all desirably minimized when an RWA is designed for usage onboard a small satellite. At the same time, any such “small scale” RWA (that is, an RWA having a reduced size and weight as compared to conventional RWAs) is also ideally structurally robust, highly reliable, and capable of being manufactured in an efficient, cost effective manner. The following describes small scale RWAs that satisfy such competing criteria.